HMS Hood did not need all 24 boilers for cruising

How many boilers did HMS Hood have, and did they all need to run at once?

Hood had 24 boilers; a few could get her moving, about half could support cruising, and all were needed for full speed.

HMS Hood had twenty-four boilers. At least four operating together could get the ship moving, so the entire plant did not need to be lit for every movement. A comfortable cruising speed might use roughly half, matching fuel and machinery effort to the required pace. Full speed called for all twenty-four.